Musical instrument having automatic arpeggio system

ABSTRACT

A musical instrument incorporates apparatus for automatically producing an arpeggio, successively producing tone in accordance with operated keys of a keyboard, in response to operation of at least one control switch. Switches operated by the keys are scanned by a scanner, and the several tones of the arpeggio are each produced by a predetermined time, by stopping the operation of the scanner as the switches corresponding to operated keys are reached in each scanning cycle. The stopping of the scanner is under control of a multivibrator having an adjustable period, to permit manual selection of the rate at which the arpeggio is produced. A plurality of mode selector switches are operable to select the mode of operation of the scanner. An arpeggio having tones extending over a range of one, two or three octaves is selectable by the mode selector switches, and the mode selector switches are also operable to select one of a variety of styles of arpeggio, including an ascending style, a descending style, and a style in which the arpeggio alternately ascends and descends. A foot switch is provided for initiating the arpeggio.

United States Patent Kniepkamp et al.

1451 Oct. 15,1974

MUSICAL INSTRUMENT HAVING AUTOMATIC ARPEGGIO SYSTEM Chicago MusicalInstrument Co., Lincolnwood, Ill.

Filed: May 7, 1973 Appl. No.: 358,164

Assignee:

3,755,608 8/1973 Deutsch 84/1.01

R26,521 2/1969 Park 84/103 Primary Examiner-Richard B. WilkinsonAssistant ExaminerStanley J. Witkowski Attorney, Agent, or Firm-Hill,Gross, Simpson, Van Santen, Steadman, Chiara & Simpson 5 7 ABSTRACT Amusical instrument incorporates apparatus for automatically producing anarpeggio, successively produc- 52 U.S. C1 84 1.01 84 1.03, 84 1.24, 1 lMIDI/G 22 mg tone 1n accordance w1th operated keys of a key- [51] Int ClGloh 1/00 Gloh board, in response to operation of at least one control[58] Field 01 l 1 17 1 24 switch. Switches operated by the keys arescanned by i a scanner, and the several tones of the arpeggio are eachproduced by a predetermined time, by stopping [56] References Cited theoperation of the scanner as the switches corresponding to operated keysare reached in each scan- UNITED STATES PATENTS ning cycle. The stoppingof the scanner is under con- 3,358,068 12/1967 Campbell 84/101 '01 of amultivibrator having an adjustable period to 3482'O27 [2/1969 Okamoto at34/103 permit manual selection of the rate at which the arg'g g'ggg g fpeggio is produced. A plurality of mode selector 602 H [1971 3532 58 5"84/I17 switches are operable to select the mode of operation 316241263H971 uchiyamam 84/103 of the scanner. An arpegg1o havlng tones extendmg3,651,729 3/1972 Adachi 84/l.l7 Over a range of one, three octavesSelectable 3,683,096 8/1972 Peterson et al.. 84/l 03 x by the modeselector sw1tches, and the mode selector 3,697,661 10/1972 Deutsch 84/1.01 switches are also operable to select one of a variety of 3,707,59412/1972 lchikawa... 84/103 styles of arpeggio, including an ascendingstyle, a de- 5 V1973 y 84/1133 scending style, and a style in which thearpeggio altera g nately ascends and descends. A foot switch is providedLIIIC e a 3,743,755 7 1973 Watson 84/1.01 for mmatmg the arpegg'o'3,743,757 7/1973 Okamoto 84/].03 19 Claims, 11 Drawing Figures 6 57305!" 4 eel m W/fC// 1 4/ UP 1... M w 1 up i r e 72%;? SCAN a0 3 5) 00age-N 1 @7755 14: 6:60 S r/Z? 0/5454: osc 7 ecu/V751? 6 g 1 I 67 KtY AEdd/V7 *0 I I M/Pur 1 z/ r "7 74 15 F ER 1 J T/Mfk 57/1127 46 /5Z Do/V/VT /9 7 awe eq l 1 ARPE'GG/U :7 y:

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SHEEIlnyg QR Q PAIENIED um 1 51914 SHEET 3 BF 8 PAIENTEDULT 1 51924SHEEI 8 [1F 8- m, QN mv\n\ lm 9w ww k wQ w 3 6K Q\u QM. -m N A g QM, NW,.Y||||| 5 HI T d w H u n u L @m v H u H m n u n m u w N w QNQDPNIQRMR 3Xj \QN www N $3 m z m m n q m \nm 5% :wmm Rm m\ N% N% m %M. MN m QMUSICAL INSTRUMENT HAVING AUTOMATIC ARPEGGIO SYSTEM BACKGROUND 1. Fieldof the Invention The present invention relates to a musical instrumentand, more particularly, to a musical instrument having means forautomatically producing an arpeggio.

2. The Prior Art A variety of mechanisms have been developed in the pastfor automatically producing an arpeggio in response to depression ofvarious keys and operation of various switches. An example of such asystem is described in the Kniepkamp US. Pat. No. 3,617,602. While suchsystems have operated satisfactorily for the purpose for which they aredesigned, a relatively large volume of structure is required, includinga large number of discrete components such as transistors, resistors,and the like.

The system described and claimed in the aforementioned Kniepkamp patentemploys an analog technique which is subject to the disadvantage thatcompromises must be made in the number of notes keyed at a single time,due to the relatively large voltage swing required when an analogtechnique is used.

Moreover, automatic arpeggio systems have thus far been limited in theiroperation to only a single operating mode, which is carried out in timedcycles, irrespective of the number of tones making up the arpeggio.

SUMMARY OF THE INVENTION According to one embodiment of the presentinvention, a musical instrument, having a keyboard and a plurality ofswitches operable by the keys of the keyboard, is provided with anautomatic arpeggio producing system incorporating a scanning oscillator,a monostable multivibrator, scanning means connected with the scanningoscillator for respectively scanning the key-operable switches, meansconnected with the scanning means and with the multivibrator fordisabling the scanning oscillator for the period of the multivibratoreach time an operated one of said key-operable switches is scanned andfor enabling the scanning oscillator at the end of said period, wherebythe tone corresponding to each of said key-operable switches is producedindividually for a time interval corresponding to the period of themultivibrator. The range of scanning is variable over one to threeoctaves by means of a plurality of mode selector switches, and thedirection of scanning is also selectable by such switches.

It is a principal object of the present invention to provide a systemfor automatically producing an arpeggio which produces each tone of thearpeggio equally spaced in time during the arpeggio.

Another object of the present invention is to produce such a system inwhich a plurality of independent modes of operation may be selected.

A further object of the present invention is to provide such a systemwhich operates by digital means, and employs apparatus which is small involume.

These and other objects and advantages of the present invention willbecome manifest upon an examination of the following description and theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Reference will now be made to theaccompanying drawings in which:

FIG. 1 is a functional block diagram of a portion of a musicalinstrument incorporating an automatic arpeggio system constructed inaccordance with an illustrative embodiment of the present invention;

FIGS. 2A-2E, taken together, comprise a composite schematic circuitdiagram, partly in functional block diagram form, of the apparatusillustrated in FIG. 1;

FIG. 3 is a functional block diagram of an up-down counter employed inthe apparatus of FIG. 1;

FIG. 4 is a functional block diagram of a one-ofsixteen decoder employedin the apparatus of FIG. 1;

FIG. 5 is a functional block diagram of a NAND gate employed in thedecoder of FIG. 4;

FIG. 6 (appearing with FIG. 3) is a functional block diagram of a J-Kflip-flop employed in the apparatus of FIG. 1; and

FIG. 7 (appearing with FIG. 2E) is an illustration of the manner inwhich FIGS. 2A-2E are to be assembled.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1, a pluralityof arpeggio keyers 10 are provided which produce 36 output signalsconnectable to a plurality of keyers (not shown) associated with theupper manual of a musical instrument such as an electronic organ. Theupper manual keyers are conventional in construction, and function tocause sources of electrical signals to be connected to an output system,which amplifies the signals and applies them to a loudspeaker or thelike, for producing musical tones corresponding to the signals. Thekeyers 10 function in response to signals developed by a plurality ofgates 14, which are connected to the input terminals of the keyers 10 bya group of lines 16. The gates 14 function, in response to outputsignals produced on lines 20 by a one-of-sixteen decoder 18, and also inresponse to output signals developed in a lower manual keyboard 22,connected to the gates 14 over lines 24. As described more fullyhereinafter, signals are produced on the lines 20 and 24 simultaneouslyin specific combinations in order to cause various output signals to beproduced by the gates 14, which cause the keyers 10 to successivelyproduce a series of output signals on the lines 12, by which an arpeggiois sounded by the output system. Each tone of the arpeggio is selectedin response to a signal present on one of the lines 20.

The inputs of the one-of-sixteen decoder 18 are derived from four outputlines 26, connected to the outputs of a four stage binary counter 28.The one-ofsixteen decoder 18 functions to energize a single one of itsoutput lines 20 in response to the binary representation present on thelines 26.

The counter 28 is caused to count a series of input pulses either up ordown, in response to operation of an up-down buffer 30. The buffer 30has an up control unit 32 and a down control unit 34, which areconnected to individual inputs of the up/down counter 28 over lines 36and 38, respectively. Only one of the control units 32 and 33 isoperative at any time, and the operative one of these two units isenabled by a signal over a line 40, which interconnects the two units 32and 33 with a plurality of mode-selector switches 42. The operative oneof the two units 32 and 33 causes pulses to pass from a scan oscillator44 over a line 46, and from the line 46 through the operative unit toeither the line 36 or the line 38. Each pulse supplied to the line 36causes the counter 28 to be incremented, that is, to increase the binaryrepresentation on the output lines 26 by unity. Similarly, pulsesapplied to the line 38 cause the counter 28 to be decremented, by whichthe binary representation on the lines 26 is decreased by unity.

The scan oscillator 44 normally operates continuously but is inhibitedfrom operating in response to a signal on a line 50 connected from astart-stop flip-flop 52. The duration of disabling of the scanoscillator 44 is controlled by the period of a timer multivibrator 54which is connected to the start-stop flip-flop 52 by a line 56. Theperiod of the multivibrator 54 is manually controllable by means of anarpeggio speed control unit 58, connected to the multivibrator 54 over aline 60.

A strobe switch 62 is connected to the scan oscillator 44 by a line 64,and functions to pass a strobe pulse from the gates 14 over a line 66,to the start-stop flipflop 52 via a line 68, a disable unit 70, and aline 74. The unit 70 normally passes strobe pulses from the line 68 tothe line 74 to set the flip-flop 52, but under certain conditions, blocksuch pulses. As more fully described hereinafter, strobe pulses areblocked when the direction of arpeggio changes from up to down, and

vice versa. The strobe switch 62 functions to pass strobe pulses fromthe line 66 to the line 68, only when the oscillator 44 is in apredetermined condition, as more fully described hereinafter. After theflip-flop 52 is set, a signal passed to the flip-flop 52 over the line56 from the multivibrator 54 operates to reset it.

An octave counter 76 is connected with the mode selector switches 42over a plurality of lines 78, and functions to present a binaryrepresentation of the number of octaves scanned by the scan oscillatorsince previously having been reset. In response to signals present onthese inputs, output signals are produced on a pair ofoutput lines 80and 82 which are connected from the switches 42 to an octave enablecontrol unit 84.

The octave enable control unit 84 is connected with the arpeggio keyersover three lines 86. The lines 86 are energized one at a time, to selectone of three octaves for operation by the arpeggio keyers 10, inresponse to the combination of signals present on the lines 80 and 82.

A rest unit 88 is provided in association with the mode-selectorswitches 42. The reset unit 88 is operated by means of a foot switch 90,and functions to reset the counter 76. A source of positive potential,connected to a terminal 92, is connected to the reset unit 88 by thefoot switch 90, in order to activate it. The foot switch is alsoconnected to a reset input of the counter 28. When the foot switch 90 isclosed, the counters 28 and 76 are both reset to zero. The counter 76 isalso controlled by signals originating with the mode-selector switches42, as more fully described hereinafter. This control is illustrateddiagrammatically in FIG. 1 by a line 89 interconnecting the switches 42with the counter 76.

Referring now to FIGS. 2A 2E, which are interrelated as illustrated inFIG. 7, the start-stop flip-flop 52 comprises a pair of transistors 102and 104, having their bases and collectors crosscoupled through a pairof resistors 106 and 108. The emitters of both transistors are connectedto ground, and the base of each is connected to ground throughindividual resistors 110. The collector of each is connected to a sourceof positive voltage applied to terminal 112 through individual resistorsL14.

The two transistors 102 and 104 conduct mutually exclusively, one beingsaturated while the other is cut off. The state in which the transistor102 is saturated and transistor 104 is cut off is hereinafter referredto as the reset state of the flip-flop 52, while the opposite isreferred to as the set state. A transistor 116 has its collectorconnected to the base of the transistor 102 and its emitter connected tothe ground, and functions to set the flip-flop 52 when a positive pulseis applied to its base by the line 74. The origin of the setting pulseis described more fully hereinafter.

A transistor 118 has its collector connected to the base of thetransistor 104 and its emitter connected to ground. This transistor isprovided for resetting the flipflop 52 to resume its reset state inresponse to a positive pulse on the line 56, connected with themultivibrator 54. The multivibrator 54 incorporates a pair oftransistors 120 and 122, having their bases and collectors cross-coupledby a pair of capacitors 124 and 126. Each emitter is connected to groundthrough an individual diode 128, and the collectors are connected to asource of positive potential at a terminal through individual resistors132. The base of the transistor 120 is connected through a resistor 134and a rheostate 136 to the terminal 130, and the base of the transistor122 is connected through a resistor 137 and a rheostat 138 to theterminal 130. The rheostates 136 and 138 are ganged together so that thebias potential applied to the bases of the transistors 120 and 122 isadjustable simultaneously by movement of the taps of the rheostats 136and 138, which together form the arpeggio speed control unit 58. Theposition of the taps of these rheostats control the frequency ofoscillation of the multivibrator 54. Preferably, its frequency isadjustable between approximately 4Hz and 20Hz.

The collector of the transistor 122 is connected through a voltagedivider incorporating resistors 140 and 142, the output of which isconnected to the base of a transistor 144. The emitter of the transistor144 is connected to ground and its collector is connected to a source ofpositive potential at a terminal 146 through a resistor 148. Thecollector of the transistor 144 is also connected through a voltagedivider incorporating resistors 150 and 152, the output of which isconnected to the base of the transistor 118 through a capacitor 154, andto ground through a resistor 156.

When the state of the multivibrator 54 is such that the potential at thecollector of the transistor 122 goes from high to low, the transistor144 is cut off, and a positive-going pulse is passed through thecapacitor 154 to the base of the transistor 118. This saturates thetransistor 118 and brings down the potential at the base of thetransistor 104 close to ground potential, resetting the flip-flop 52.The flip-flop 52 is thus reset by the transistor 118 at the instant thatthe multivibrator 54 assumes the state in which the collector of thetransistor 122 is low.

A diode 158 is connected from the collector of the transistor 102 to theline 50, and a diode 162 is connected from the collector of thetransistor 144 to the line 50. When either of the transistors 102 or 144is cut off, current flows through one of these diodes to the line 50.The line 50 is connected to the base of a transistor 164 by a resistor166. The emitter of the transistor 164 is grounded and its collector isconnected to the base of a transistor 168. The transistor 168 and asecond transistor 170 form the scan oscillator 44. The bases andcollectors of the transistors 168 and 170 are cross-coupled throughcapacitors 172 and 174. The collectors of the transistors 168 and 170are each connected to a positive source of potential at a terminal 176through individual resistors 178. The bases of the two transistors areconnected to the terminal 176 through individual resistors 180.

The scan oscillator 44 functions in the same manner as the multivibrator54, that is, as an astable or freerunning multivibrator producing anoutput square wave at a frequency dependent upon the RC time constant ofthe circuit. The frequency of the oscillator 44 is much higher than thatof the multivibrator 54, however, and is preferably about lkHz.

When the transistor 164 is saturated, by a positive signal appliedthereto over the line 50 (when the flipflop 52 is set), the collector ofthe transistor 164 is held close to ground potential, and the scanoscillator 44 is thereby disabled by maintaining the transistor 168 inits cut off condition. A positive pulse is produced on the line 50 whenthe collector of the transistor 102 goes high in response to a positivepulse on the line 74, applied to the base of the transistor 116, and thescan oscillator 44 is thereafter disabled until the flip-flop 52 isreset.

The collector of the transistor 170 is connected over the line 64through a voltage divider comprising resistors 184 and 188 to the baseof a transistor 186, which functions as the strobe switch 62. Theemitter of the transistor 186 is connected to ground through a diode190. and its collector is connected through a resistor 192 to the line66.

The collector of the transistor 186 is also connected through acapacitor 196 and a pair of resistors 198 and 200 to the line 74, and tothe base of the transistor 116, and also to ground through a resistor202. As the transistor 116 is responsible for setting the start-stopflipflop 52, it is apparent that the positive-going pulse over the line74 which functions to set the flip-flop 52 is derived from the line 66.However, this pulse cannot reach the transistor 116 as long as thetransistor 186 is conducting. since the collector of the transistor 186is at that time held close to ground potential. Accordingly, theflip-flop 52 can only be set via the transistor 116 when the scanoscillator 44 is in its state in which the collector of the transistor170 is low, cutting off the transistor 186. The collector of thetransistor 168 is then at a high potential.

The scan oscillator 44 furnishes pulses which change the state of thecounter 28. These pulses are derived from the collector of thetransistor 168, and passed by the line 46 to the inputs of the bufferunit 30, which includes an up counting unit 32 adapted to furnish pulsesfor incrementing the counter 28, and a down counting unit 33 adapted tofurnish pulses which decrement the counter 28. The counter 28 ispreferably a type such as theTexas lnstruments SN74193, which is adaptedto be counted up or down in response to positive-going pulses applied toinput terminals 206 and 208, respectively, provided the other inputterminal in simultaneously held at a high potential. It is the functionof the buffer unit 30 to apply pulses to the terminals 206 and 208 ofthe counter 28 while maintaining an elevated potential at the unusedterminal.

The line 46 is connected through a voltage divider including resistors210 and 211 to the base of a transistor 212, the emitter of which isgrounded and the collector of which is connected, through a resistor214, to a positive source of potential at a terminal 216. Thetransistors 212 functions as an inverter and is adapted to provide apositive-going pulse to the terminal 206 of the counter 28 in responseto a negative-going pulse on the line 46. The line 46 is also connectedthrough a voltage divider including resistors 217 and 219 to the base ofa transistor 218, the emitter of which is grounded and the collector ofwhich is connected through a resistor 220 to a source of positivepotential at a terminal 222. The collector of transistor 218 isconnected to the terminal 208 and is adapted to provide positive-goingpulses to the terminal 208 in response to negative-going pulses presenton the line 46. Only one of the two transistors 212 and 218 is enabledat any given time, in response to the potential on the line 40.

The line 40 is connected through a voltage divider including resistors226 and 230 to the base of a transistor 228. The emitter of thetransistor 228 is grounded and its collector is connected to the base ofthe transistor 212. Accordingly, when a high potential is applied to theline 40, the transistor 228 is saturated and the transistor 212 isrendered ineffective to supply pulses to the terminal 206. When a lowpotential is present in the line 40, however, the transistor 212 iseffective to pass incrementing pulses to the counter 28.

The line 40 is also connected through a voltage divider includingresistors 232 and 236 to the base of a transistor 234. The emitter ofthe transistor 234 is grounded and its collector is connected through aresistor 238 to a source of positive potential at a terminal 240. Itscollector is also connected to the base of a transistor 235, the emitterof which is grounded and the collector of which is connected to the baseof the transistor 218. Accordingly, when the potential on the line 40assumes a low value, the transistor 234 is cut off and the transistor236 is saturated, disabling the transistor 218. When the potential onthe line 40 is high, however, the transistor 218 is effective to passdecrementing pulses to the counter 28.

The up/down buffer 30 is thus adapted to provide pulses at the properpolarity to the input terminals 206 and 208, in accordance with thepotential on the line 40, connected from the mode-selector switches 42.

The four outputs of the counter 28 appear on lines 260 26d, and they areconnected to the four inputs of the one-of-sixteen decoder 18. Theone-of-sixteen decoder 18 produces a low level of one of its 13 outputs20a 20r. Only 13 of the 16 possible outputs of the decoder 18 are used,and the other three are unconnected. 12 lines, 20a 420m, are applied toinputs of the keyers l0, and a thirteenth output 20r is connected to theline 19 which is connected to the input of the octave counter 76 (FIG.2D). The 12 outputs, 20a 20m, correspond to the 12 musical tones of anoctave. Each is connected to one of the gate transistors 14a 14m. Forexample, the line 20a is connected from an output of the decoder 18through a resistor 244a to the base of the transistor 14a. The emitterof this transistor is grounded and its collector is connected through aresistor 2460 to a terminal of a switch 22a which is closed bydepression of a particular key of the lower manual. The other terminalof the switch 220 is connected to a source of positive potential at aterminal 248, so that, when the switch 220 is closed, a positivepotential is applied to the collector of the transistor 140. When thisoccurs at the same time that a low potential is applied on the line 200,a high level signal appears on the line 160. The line 16a is connectedthrough a diode 249a to the line 66, and through a resistor 2500-1 tothe base of a transistor 2420-1, the collector of which is connected toa source of positive potential at a terminal 254, and the emitter ofwhich is connected through a diode 2560-] to the line 120-1. The line120-1 is connected to the upper manual keyer 2580-1 which is adapted tointerconnect an output of the signal generator 260-to the output systemof the muscial instrument.

The twelve switches 22a-22m are closed individually in response todepression of any one of the several octavely related keys of the lowermanual. Thus, depression of any C key closes the switch 220; depressionof any B key closes the switch 22b; etc.

In similar fashion the collector of the transistor 140 is connectedthrough a resistor 2500-2 to the base of a transistor 2520-2, thecollector of which is connected to the terminal 254 and the emitter ofwhich is connected through a diode 2560-2 to an output line 120-2. Theoutput line 120-2 is connected to a keyer 2580-2 which is adapted toconnect an output ofthe signal generator 260 to the output system of theinstrument. The tone produced by operation of the keyer 2580-2 is oneoctave higher than that produced by the keyer 2580-1.

The collector of the transistor 14a is also connected through a thirdresistor 2500-3 to the base of a transistor 2520-3. The collector of thetransistor 2520-3 is connected to the terminal 254 and its emitter isconnected through a diode 2560-3 to the output line 120-3. The line120-3 is connected to a keyer 2580-3, adapted to connect another signalfrom the signal generator 260 to the output system of the instrument.The tone produced thereby is one octave higher than the tone produced inresponse to the keyer 2580-2. The keyers 2580-1, 2580-2 and 2580-3 areconnected to a line 262. The line 262 is connected to th input of thevoicing unit 264 and the output of the voicing unit 264 is connectedthrough an amplifier 266 to a loud speaker 268.

A switch 270 is connected from a source of positive potential at aterminal 272 to the control input of the keyers 25811-3, and is adaptedto operate the keyer 2580-3 independently of the arpeggio system. Theswitch 270 is closed by a key of the upper manual of the musicalinstrument. Accordingly, the keyer 2580-3 may be operated either by theupper manual key switch 270 directly, or by the arpeggio keyer 10.Corresponding switches are provided for the other two keyers 2580-2 and2580-3, and they are also operated by the appropriate keys of the uppermanual.

As shown in FIGS. 2A 2E, either of the other gate transistors 14b 14mare connected through three individual keying transistors. It will beunderstood that these transistors are connected to others of the 36output lines of the keyer unit 10, and that such output lines areconnected to keyers adapted to connect individual outputs of the signalgenerator 260 to the output system of the instrument. Each of the gatetransistors 14b 14m leads to three octavely related keyers associatedwith the generator 260.

The base of the transistor 2520-1 is connected by a diode 274-1 to aline 86-1. In similar fashion, the bases of the transistors 2520-2 and2520-3 are connected by diodes 274-2 and 274-3 to lines 86-2 and 86-3.Only one of the three lines 86-1 to 86-3 is high at any given time, sothat only one of the three transistors 2520-1, 2520-2, and 252a-3 isable to conduct.

When the arpeggio system is not in use, the counter 28 is reset to itszero position, and the four output lines 260 260 in this case cause thedecoder 18 to manifest a low potential on the output line 20r, and ahigh potential on all the remaining lines 200 20m. The transistors 14014m are all saturated and the switches 22a 22m are ineffective tooperate the keyers 10. However, an additional set of switches, of whichonly the switch 22'0 is shown, are also actuated by the keys of thelower manual, and they are connected to appropriate ones of the keyersto complete electrical circuits from the signal generator 260, or fromanother signal generator (not shown), through appropriate voicingcircuits and then to the amplifier 266. Thus the keys of the lowermanual are usable in the conventional manner when the arpeggio system isnot in use.

The foot switch 90 establishes a connection from a source of positivepotential at a terminal 276 through a diode 278, and through a voltagedivider including resistors 280 and 282, to the reset terminal 284 ofthe counter 28. When it is desired to operate the arpeggio circuit, thefoot switch 90 is operated to disconnect the reset terminal 284 from theterminal 276, allowing the counter 28 to be incremented or decremented.

The scan oscillator 44 normally operates continuously to provide asquare wave on the line 46 which, when the up counting unit 32 isoperative, provides a continuous sequence of pulses applied to theterminal 206 to successively increment the counter 28 when the footswitch 90 is open. This causes repetitive scanning of the lines 200-20mconnected to the outputs of the decoder 18, each line being scanned bylowering its potential while maintaining the potential of the othershigh.

Once during each cycle of the counter 28, the output line 20r is low,producing a pulse on the line 19 which increments the octave counter 76.The octave counter 76 is illustrated in FIG. 2D, along with a diodeselection matrix 298 which functions to decode the output signalsproduced by the counter 76, and to energize one of several controllines, for programming operation of the system in a series of steps. Theline 19 is connected to the clock input of a J-K flip-flop 284. The Jand K inputs of the flip-flop 284 are connected in common through aresistor 286 to a source of positive potential at a terminal 288. Theflip-flop 284 is therefore triggered by each pulse applied to the line19, changing its state on the negative-going edge of each pulse.

The Q output of the flip-flop 284 is connected by a line 290 to theclock input of a J-K flip-flop 292. Similarly, the Q output of theflip-flop 292 is connected by a line 294 to the clock input of aflip-flop 296. The J and K inputs of the flip-flops 292 and the K inputof the flip-flop 296 are connected in common with those of the flip-flop292. The J input of the flip-flop 296 is connected to the terminal 288through a separate resistor 297. The three flip-flops comprise a threestage binary counter. Six outputs are derived from the counter, and

are connected from the Q and O outputs of each of the flip-flops 284,292 and 296 to six lines of the diode matrix 298, which is provided fordecoding the state of a counter 76 and producing a high level on one ofseven output lines 301-307, in accordance with the instantaneous stateof the counter 76.

Each of the seven output lines 301-307 is connected through a separateresistor 308 to a positive potential at a terminal 310. The line 301 isconnected to the anodes of three diodes 312, 314 and 316, the cathodesof which are connected, respectively, to the three Q outputs of theflip-flops 284, 292 and 296. Accordingly, the level on the line 301 goeshigh when all of flip-flops 284, 292 and 296, have high potentialsapplied to their 6 outputs, so that all three diodes 312, 314 and 316are blocked. When the counter 76 is in another state, one or more of thethree diodes 312, 314 and 316 conducts, clamping the potential of theoutput line 301 substantially to ground. Each of the lines 302-307 isconnected in a similar fashion, to decode one individual state of thecounter 76. Each of the lines 302-307 is connected to three individualdiodes which are connected to a unique combination of the O and Qoutputs of the counter 76. The lines 301-307 are energized successivelyin numerical order as the counter 76 is incremented by the pulsesapplied thereto on the line 19.

When the counter 76 manifests a binary 6, in which the O output of theflip-flop 284 is high and the outputs of the flip-flops 292 and 296 arehigh, the line 307 goes high, passing a positive pulse through a diode318 to the base of a transistor 320. The emitter of the transistor 320is connected to ground and its collector is connected to a source ofpositive potential at a terminal 322 through a resistor 324. Thetransistor 320 saturates in response to the positive pulse passed by thediode 318, and the potential at its collector is reduced substantiallyto ground. The collector is connected by line 326 to the reset inputs ofthe flip-flops 284, 292, 296, so that the instant that the counter 76manifests a binary 6, it is reset to binary zero. Therefore, the radixof the counter 76 is limited to six, and the six output lines 301-306are all energized for approximately equal periods during each cycle ofoperation of the counter 76. The counter 76 is also reset by the footswitch 90, by connecting the terminal 276 to the line 442 via a diode440. The line 442 is connected to the base of the transistor 320 througha voltage divider including resistors 444 and 446.

As the pulses applied to the input of the counter 76, via the line 19,are derived from the output line r of the decoder 18, the counter 76 isincremented during each complete scan of the output lines 20a-20r of thedecoder 18. which occurs during each complete cycle of operation of thecounter 28. This corresponds to the scan of one complete octave of 12adjacent keys ofthe lower manual, so that the count manifested in thecounter 76 corresponds to a binary representation of the number ofcomplete octaves scanned during the period following the resetting ofthe counter 76. The signals applied to the lines 301-306 thereforecorrespond to time intervals related to particular octaves which arescanned following resetting of the counter 76. These lines are appliedas inputs to the mode selector switches 42 (FIG. 2E) for the purpose ofcontrolling the operation of the system in a variety of different modes.

Five individual mode selecting switches 331-335 are provided in thegroup 42. Each of the switches 331-335 is a 6 pole double-throw switch,as illustrated. When any one of the switches is selected by movement ofits respective actuator 33l-335', all of its poles simultaneously changetheir condition from that illustrated in FIG. 2E to the oppositecondition. The switches are interconnected in a network so that aplurality of control signals are developed in response to variouscombinations of input signals. Lines 301-306 are connected to six inputsof the network, each being representative of a unique state of thecounter 76. Another input is supplied over a line 336, connected fromthe Q output of the flip-flop 284 (FIG. 2D).

One output of the network is provided on a line 338, connected to theline 40 to control the direction of the up-down counter 28. Anotheroutput is provided on a line 340 which is connected to the J input ofthe flipflop 296. The two lines and 82 are connected as outputs forcontrolling the selection of one of the three octaves by the keyers 10.A final output line 342 is provided, connected through a diode 344 tothe line 50 (FIG. 2A), for the purpose of disabling the scan oscillator44 when none of the switches 331-335 have been operated.

When the first switch 331 is selected, an Up-Only arpeggio mode isperformed, in which an arpeggio process is produced over a range ofthree octaves, beginning with the lowest selected note of the firstoctave and extending through the highest selected note of the thirdoctave. When the second switch 332 is actuated, the circuit performs aDown-Only mode, in which an arpeggio is produced which extends overthree octaves, beginning with the highest selected note in the highestoctave and ending with the lowest selected note in the first octave.Notes are selected in accordance with the keys 22a-22m of the lowermanual which are operated, and each selected note is played individuallyin succession, each for substantially the same duration. The same notesare played in each octave as a result of the three keying transistors ofthe keyers 10 which are connected to each output line 16 of the gates18.

The third switch 333 selects an Up-Down One Octave mode, producing anarpeggio which begins at the lowest of the first octave and movesupwardly through the first octave to the highest selected note, and thenreturns downwardly therethrough to the lowest selected note, repeatingthe cycle as many times as desired. When the switch 334 is actuated anUp-Down Two Octave mode is selected, in which an arpeggio is producedwhich extends upwardly through the first and second octaves and thendownwardly through the second and first octaves, repeating the processover and over. The switch 335 selects an Up-Down Three Octave mode, inwhich the arpeggio extends upwardly through all three octaves and thendownwardly through all three octaves, repeating the process over andover.

When the Up-Only mode is selected, by depression of the switch 331, thefirst pole 331a interrupts the circult extending from the line 301 tothe output line 342. The line 301 is high during the first octave, whilethe state of the octave counter 76 is zero, having been reset over theline 442 by means of the foot switch 90. The positive potential normallyapplied over the line 342 through the diode 344 to the line 50 (FIG. 2A)maintains the scan oscillator 44 in disabled condition, while the octavecounter 76 is in its 0" state. Disconnection of this circuit by means ofthe first pole of switch 331' however, permits the scan oscillator 44 tofunction, with a result that pulses are supplied over the line 46through the counting unit 32 to increment the counter 28 once duringeach cycle of the oscillator 44. This condition persists through anentire cycle of the counter 28, at the end of which the line 19 receivesa signal from the decoder 18, and the counter 76 is incremented to itsbinary l state.

The line 302 is provided with a high potential during the binary l stateof the counter 76, and by operation of the second pole 33112 of theswitch 331 this potential is applied to the line 80, which causes theoctave enable control unit 84 to raise the potential on the line 86-2,and lower the potential on the line 86-1, which was high while thecounter 76 was in its zero state. The scan oscillator 44 continues tofunction, so that the counter 28 is continually incremented and thesecond octave is scanned by successively energizing outputs of thedecoder 18. As the line 86-2 has a high potential, outputs for keyingnotes in the second octave are supplied over the output lines 12 of thekeyer 10. At the end of the second octave the line 19 is again pulsed toincrease the state of the counter 76 to binary This produces a highpotential on the line 303, which is connected by the third pole 3316 ofthe switch 331 to the output line 82. The octave enable control unit 84then raises the potential on the line 86-3, permitting keying of thethird octave keyers during the next scan of the decoder 18.

At the end of the scan of the third octave, the line 19 again isprovided with a pulse to increment the counter 76 to its binary 3 state,at which time the line 304 goes high. This line is connected through thefourth pole 331d of the switch 331 to the output line 342. This places ahigh potential on the line 50 via the line 342 (FlG. 2A) which saturatesthe transistor 164 and disables the scan oscillator 44, so that nofurther scanning occurs. while the octave counter is in it binary 3state. As the scan oscillator 44 is disabled, no further pulses appearon the line 19 and the counter 76 remains in its binary 3" state untilagain reset by operation of the foot switch 90.

The fifth pole 331a of the switch 33] connects the output line 338 toground, to cause the buffer 30 to pulse only the input 206 of thecounter 28. The sixth pole 33lf of the switch 331 limits the radix ofthe counter 76 to 4, so that the next pulse applied to the input line 19of the counter 76 resets the counter to its zero state rather thanincrementing it to its binary 4 state. This is accomplished byconnecting the J input of the flip-flop 296 to ground so that it remainsin its reset state even after a pulse is supplied to the line 294.

When the Down-Only mode switch 332 is actuated, the first pole 332a ofthe switch 332 interrupts the circuit between the input line 301 and theoutput line 342, and instead connects the input line 301 to the outputline 82, to enable the third octave during the time that the counter 76is in its state. The fifth pole 332e of the switch 332 connects theoutput line 338 to a source of positive potential at a terminal 344, sothat the line 40 is maintained at a high potential, permitting theapplication of pulses to the down counting input terminal 208.

The second pole 332b of the switch 332 connects the line 302, which ishigh while the counter 76 is in its binary l state during which thesecond octave is scanned, to the output line 80, permitting the octaceenable control unit 84 to raise the potential on the line 86-2. Thethird pole 332C of the switch 332 disconnects the line 303, which ishigh during the binary 2" state, from any output line. As a result theoutput lines and 82 are both low during the time that the third octaveis scanned, whileathe counter 76 is in its binary 2 state, permittingthe octave enable control unit 84 to raise the potential on the line86-1 to select the first octave of the keyer 10. The fourth pole 332d ofthe switch 332 connects the input line 304 to the output line 342 todisable the scan oscillator 44 when the scan of the first octave iscomplete.

The sixth pole 332f of the switch 332, like that of the switch 331,limits the radix of the counter 76 to 4, so that the next pulseappearing on the line 19 does not set the flip-flop 296.

When the switch 333 is actuated, an Up-Down One Octave mode is selected.The first pole 333a of the switch 333, like that of the other switchesdescribed above, opens the connection between the input line 301 and theoutput line 342. The second pole 333b of the switch 333 interrupts anyconnection of the input line 302. Similarly, the third pole 3330 of theswitch 333 interrupts any connection of the input line 303 and thefourth pole 333d interrupts any connection of the input line 304. Thefifth pole 3336 of the switch 333 connects the input line 336 with theoutput line 338. As the level on the input line 336 changes with eachpulse applied to the counter 76 over the line 19, the state of theoutput line 338 is caused to change in a corresponding manner, with aresult that the counter 28 is counted up during the first octave scannedand then counted down during the second octave scanned, after which theoperation is repeated continuously until the switch 90 is closed, afterwhich the counter is held in its zero state. The sixth pole 333fof theswitch 333, like those of the switches 331 and 332, limits the radix ofthe counter 76 to 4, to maintain the flip-flop 296 in its reset state.Neither the output lines 80 and 82 are high at any time while the switch333 is actuated so that only the first octave of the keyer circuits 10is selected by the control unit 84.

When the switch 334 is actuated, its first pole 334a interrupts theconnection between the input line 301 and the output line 342, just asdescribed above. The second pole 33417 of the switch interconnects theinput line 302, which is high during the scanning of the second octave,to the output line 80, which brings about a high potential on the line86-2. The third pole 334C of the switch 334 connects the input line 303through a diode 346 to the output line 80, so that the high potential onthe line 86-2 continues. Simultaneously a diode348 connects the inputline 303 to the output line 338, through a series connection includingthe fifth poles 331e-333e of the switches 331, 332 and 333, to provide ahigh potential on the line 338 while the counter is in its binary 2state, to enable the counter 28 to be counted downwardly.

The fourth pole 334d of the switch 334 connects the input line 304 withthe output line 338 to continue the high potential applied to the line338 while the counter 76 is in its binary 3 state.

The fifth pole 334e of the switch 334 is not functional and the sixthpole 334f limits the radix of the counter 76 to 4, as described above.

When the switch 335 is energized, to select the Up- Down Three Octavemode, the interconnection between the input line 301 and the output line372 is broken by the first pole 335a of the switch, in the same manneras described above. The second pole 335b of the switch 335 connects theinput line 302 to the output line 80 to present a high potential on theline 86-2, allowing the keyers of the second octave to be operated. Thethird pole 3356 of the switch 335 interconnects the input line 303 withthe output line 82 to produce a high potential on the line 86-3, toenable the third octave of the keyers to be operated while the counter76 is in the binary 2 state. The fourth pole 335d of the switch 335connects the input line 304 through a diode 350 to the output line 82 tocontinue to present a high potential on the line 86-3 while the counter76 is in its binary 3 state. Simultaneously the input line 304 isconnected by a diode 352 to the output line 338 through the fifth poleof each of the switches 331, 332 and 333, to select the down countingdirection for the counter 28.

The fifth pole 335e of the switch 335 connects the input line 305through a diode 354 to the output line 80 to operate the second octaveof the keyers 10 by raising the potential on the line 86-2. The diode356 also connects the input line 305 to the output line 338 through thefifth poles of the switches 331, 332 and 333 to maintain the downwardcounting direction of the counter 28 while the counter 76 is in itsbinary 4 state. The switch pole 33Sfof the switch 335 connects the inputline 306 to the output line 338 through the fifth poles of the switches331, 332 and 333 to maintain a downward counting direction while thecounter 76 is in its binary 5" state. The next pulse applied to theinput of the counter 76 over the line 19 briefly places the counter inits binary 6 state, but the transistor 320 immediately resets it to itszero state, so that the operation described above can be repeated.

The output line 342, which results in disabling the scan oscillator 44after a single arpeggio cycle, is energized while the counter 76 is inits *3 state only when the switches 331 and 332 are actuated.Accordingly, the up-down modes selected by the switches 333, 334 and 335are continuous and the arpeggio produced when these switches areactuated is performed continuously as long as any of the lower manualswitches 22 are closed. The actuators 33l'335' of the switches 331-335are preferably of the push button, or rocker switch type. located withineasy access of the player of the instrument, so that any one of them isselectable at the convenience of the operator. The actuators may beprovided with mechanical interlock means (not shown) for resetting theunselected switches to unactuated condition upon the selection of anyswitch by depressing its actuator. As such interlock means is wellknown, it need not be specifically described here. When such aninterlock means is not used, depression of two or more of the actuators331-335 is effective to produce an arpeggio in the same manner as ifonly one of such actuators was depressed. that one being the actuatorfor the switch which is shown in a position furthest to the left in FIG.2E. Therefore, if the switch 331 is operated, operation of any oherswitch does not vary the mode selected; if the switch 332 is operated,no other switch can vary the selected mode, except for the switch 331;and so forth.

The octave enable control unit 84 is connected with the two lines 80 and82 from the mode selector switches 42, and with the lines 86-1 and 86-2and 86-3.

The unit 84 functions to maintain two of the output lines at a lowpotential and to raise the potential of the third output line.

The octave enable control unit 84 includes a transistor 360 which hasits base connected by a resistor 362 to the line 80. The collector ofthe transistor 360 is connected through a resistor 364 to a source ofpositive potential at a terminal 366, and the emitter of the transistor360 is grounded. The collector of the transistor 360 is connected to thebase of a transistor 368, the emitter which is grounded and thecollector of which is connected to the output line 86-2. Accordingly,when the input line 80 is high, the transistor 360 is saturated, and thetransistor 368 is cut off, effectively removing diodes 274-2, etc., fromthe circuit. The potential applied from any of the collectors of thetransistors 14a 14m will then be applied through resistors 250a-2, etc..to the corresponding bases of transistors 252a 252m. When the potentialon the line 80 is low, the transistor 360 is cut off, thereby saturatingthe transistor 368 and maintaining the line 86-2 at a low potential.

A similar circuit is connected to the input line 82. A transistor 370has its emitter grounded and its collector connected through a resistor372 to a positive potential at a terminal 374. The base of thetransistor 372 is connected to the line 82 through a resistor 376. Thecollector of the transistor 370 is connected to the base of a transistor378, the emitter which is grounded and the collector of which isconnected to the line 86-3.

A pair of diodes 380 and 382 have their anodes connected respectively tothe lines 80 and 82 and their cathodes connected in common and through aresistor 384 to the base of a transistor 386. The emitter of thetransistor 386 is grounded and its collector is connected to the line86-1. Accordingly, when either of the input lines 80 and 82 is high, thetransistor 386 is saturated and the line 86-1 is clamped to ground. Whenneither of the input lines 80 and 82 is high, however, the transistor386 is cut off and the diodes connected to the line 86-] are effectivelyremoved from the circuit.

When any ofthe switches 333, 334, and 335 are actuated the arpeggiokeyer is operated continuously in an up and down direction as describedabove. As reversal of the scanning direction occurs only after a pulseis produced on the line 19, the first one of the operated keys 22 to bescanned after reversal is the same as the last operated key to bescanned before reversal. in order to prevent the tone produced in theoutput system from being sounded twice in succession, in production ofthe arpeggio, which is undesired, the disable circuit is provided. Areversal in the direction of scan is signaled by a change in state onthe line 338. The line 338 is connected by a line 72 to a voltagedivider (FIG. 2B) including resistors 390 and 392, and the output of thevoltage divider is connected to the base of a transistor 394. Theemitter of the transistor 394 is connected to ground and its collectoris connected through a resistor 396 to a source of positive potential ata terminal 398. The collector is also connected through a resistor 400to the base of a transistor 402. The emitter of the transistor 402 isgrounded and its collector is connected to a source of positivepotential through a resistor 404 at a terminal 406. The transistor 394functions as an amplifier and the transistor 402 functions as aninverter. Equal and opposite signals are thus provided at the collectorsof the two transistors 394 and 402.

The collector of the transistor 394 is connected through a capacitor 408to the anode of a diode 410. The cathode of the diode 410 is connectedto one terminal of a capacitor 412, the other terminal being connectedto ground. Similarly, the collector of the transistor 402 is connectedthrough a capacitor 414 to the anode of a diode 416, the cathode ofwhich is connected to the ungrounded terminal of the capacitor 412. Bothcapacitors 414 and 408 are clamped to ground individually by a pair ofdiodes 418, to bypass negative-going pulses passed by the capacitors 408and 414.

The capacitors 408 and 414 function as differentiator circuits, so thata positive going pulse is passed by one of the diodes 410 and 416 andapplied to charge the capacitor 412, each time the collector of itsassociated transistor goes high. The collector of the transistor 394goes high whenever there is a negative-going change in potential on theline 72, and conversely, the collector of the transistor 402 goes highwhenever there is a positive-going change in potential on the line 338.Thus, each time there is a change in the level of potential on the line338, a positive pulse is applied to the capacitor 412.

A resistor 420 is connected in parallel with the capacitor 412. Thevalue of the resistor 420 is relatively high, so the capacitor 412maintains substantially its full charge during the interval between twosuccessive pulses on the line 66, which is equal to approximately oneperiod of the multivibrator 54.

The ungrounded terminal ofthe capacitor 412 is connected through aresistor 422 to the base of a transistor 424, the emitter of which isgrounded and the collector of which is connected to the junction of theresistors 198 and 200. While the capacitor 412 remains charged, thetransistor 424 is saturated, maintaining the potential at the junctionof the resistors 198 and 200 substantially at ground. Accordingly, apulse appearing on the line 66 is prevented from producing apositive-going pulse on the line 74, since the transistor 424 clamps themost positive potential which can exist on the line 74 to substantiallyground potential. As a result, the capacitor 196 is charged to thepotential corresponding to the height of the pulse on the line 66. Whenthe positive-going pulse on the line 66 ends, the capacitor 196 isdischarged through resistors 198, 200, and 202, and while doing so,produces a negative potential on the line 74. The line 74 is connectedthrough a capacitor 426 to the base of a transistor 428. The transistor428 is normally biased into conduction by current flowing through aresistor 430, connected between the base and a source of positivepotential applied to a terminal 432. The negative potential on the line74 cuts off the transistor 428, which produces a positive pulse at itscollector. The collector of the transistor 428 is connected through aresistor 434 to the terminal 432, and to the base of a transistor 436,the emitter of which is grounded and the collector of which is connectedto the ungrounded terminal ofthe capacitor 412. Accordingly, thetransistor .436 is operative to discharge the capacitor 412 in responseto the negative potential on the line 74. The capacitor 412 thereafterremains dishcarged until the succeeding change in potential on the line338. Thus, only one strobe pulse is prevented from reaching the line 74following a change of potential on the line 338, and subsequent pulsesare not inhibited.

The omitted strobe pulse is the one which is produced when the firstoperated switch 22 is scanned following the reversal in the direction ofcounting of the counter 28. The flip-flop 52 therefore is not set bythis pulse. In this way successive retriggering of the same tone in anarpeggio is avoided.

In operation, when the foot switch is operated to break the connectionfrom the terminal 276 to the anodes of the diodes 278 and 440, thecounters 28 and 76 are no longer maintained in their reset condition andare able to count pulses produced by the scan oscillator 44 and pulsesproduced at the output 20r of the decoder 18. This operation continues,with successive output lines 20a-20m going low, until a line is reachedwhich is connected in circuit with an operated one of the switches22a-22m. When this occurs, the corresponding one of the lines 16a-16mgoes high, producing a strobe pulse on the line 66', via one of thediodes 249a 249m.

The strobe pulse on the line 55 is defined by a high potential on theline 66, which begins at the instant that the counter 28 assumes thestate corresponding to the output of the decoder 18 being scanned, whichcoincides with the condition in which both input terminals 206 and 208are high. This occurs when the collector of the transistor 168 (FIG. 2A)of the scan oscillator 44 is low, corresponding to a high level on theline 64. The strobe switch 62 (FIG. 2B) is thereby disabled, until thestate of the oscillator 44 changes and the potential on the line 64 goeslow. The state of the counter 28 does not change when this happens, sothat the potential on the line 66 remains high, and a strobe pulse ispassed to the line 74, setting the flip-flop 52 and disabling the scanoscillator 44 by holding it in the state just described. At the time thestrobe pulse is produced on the line 74, the multivibrator 54 is in thestate in which the potential present at the collector of the transistor122 is high, so a low potential is present at the collector of thetransistor 144. Otherwise the scan oscillator 44 remains disabled by ahigh potential on the line 50. The scan oscillator 44 remains disabled,as a result of the flip-flop 52 until the end of the half cycle of themultivibrator 54, at which time the flip-flop 52 is reset via thetransistor 118. However, the scan oscillator 44 remains disabled by themultivibrator 54, until at the end of its next half cycle, when thepotential on the line 50 again goes low.

Therefore the counter 28 maintains its count for nearly an entire cycleof the multivibrator 54, being less than that interval only by theperiod required to advance the counter 28 until the next operated one ofthe switches 22 is reached. As the frequency of the scan oscillator 44is much higher than that of the multivibrator 54, the period requiredfor advancing the counter 28 is much less than one cycle of themultivibrator 54. In the interval in which the scan oscillator 44 isdisabled, the output of the decoder 18 remains constant, thus operatingone of the keyers 10, the associated transistor 252a-l through 252m-3energizing the associated keyer 258, etc. Upon resumption of the scanoscillator 44, scanning continues, under the control of the modeselector switches 42, until another operated switch 22 is encountered.

The relatively high frequency of the scan oscillator 44 results in anapparent zero delay between successive tones of the arpeggio, each ofwhich is sounded for substantially the same interval. There is,therefore, no socalled loping, an undesirable feature characteristic ofsystems in which the scanning rate is uniform, both between tones andduring tones.

When the Up-Only mode is selected, the scanning begins at the bottom ofthe first octave and continues upwardly through three octaves and tonesare sequentially sounded corresponding to selected keys in each of threeoctaves. Thereafter, operation ceases until after the counters, 28 and76, are reset by operation of the foot switch 90, after which theoperation is repeated once, and then stopped again.

When the switch 332 is selected, the operation is identical, except thatscanning occurs downwardly beginning with the upper end of the highestoctave and ending with the lower end of the lowest octave.

When any of the three remaining selector switches are actuated, scanningis continuous in an up, then down, then up, etc., sequence. The range ofthe scanning is under control of the switches 42, and extends for onceoctave when the switch 333 is actuated, for two octaves when the switch334 is actuated, and for three octaves when the switch 335 is operated.The arpeggio produced is continuous until the keys which operate theswitches 22 are released or until the foot switch 90 is closed.

It will be appreciated that the arpeggio system of the present inventiondoes not interfere in any way with normal operation of the musicalinstrument. The lower manual key switches such as 22'a are functional inthe ordinary way to permit signals to be selected for connection to theoutput system, through voicing circuits selector therefor, in responseto depression of the keys of the lower manual. Similarly, switches likethe switch 270 of the upper manual are effective to operate the keyerslike the keyer 258a-l, etc., in the conventional way, to produce tonesnormally associated with the upper manual. As long as the foot switch 90remains closed, the counters 28 and 76 remain reset, and the arpeggiosystem does not function, while permitting ordinary operation of theinstrument.

Referring now to FIG. 3, a functional block diagram of the counter 28 isillustrated. This counter is like a commercially available counter, suchas the Texas Instruments SN74193 incorporating the functional equivalentof four flip-flops 441-444, each of which has its clock input connectedto one of four OR gates 445-448. The two inputs of the OR gate 445 areconnected individually through a pair of inverters 449 and 450 from apair of input terminals 451 and 452. Inputs supplied to the terminal 441function to count the four stage binary counter made up of the fourflip-flops 441-444, connected in cascade, in a normal upward countingdirection. Input pulses applied to the input terminal 452 result in thecounter being decremented once for each pulse so applied. Three OR gates446-448 each have two inputs connected to the output of an individualpair of six NAND gates 453-458. The NAND gates 453-458 are eachconnected to the Q and Q outputs of an individual one of the flip-flops441-443, and are individually energized in response to the outputs ofone of the two inverters 449 and 450. Three of the NAND gates areconnected to the inverter 449 and the other three of the NAND gates areconnected to the inverter 450. One set of these are enabled forconduction at any given time, depending on which of the input terminals451 and 452 has pulses applied thereto. An additional inverter 459 isconnected from an input terminal 460 to the reset inputs of each of theflip-flops 441-444, to reset the state of the counter in response to areset pulse present at the terminal 460.

FIG. 4 is a functional block diagram of the decoder 18, which is similarto a commercially available unit such as the Texas Instruments SN74154.Four inputs are applied to input lines 461-464, and four inverters465-468 have their input terminals connected to the input lines 461-464.13 NAND gates 469 are provided, each having four input terminals. 16output terminals 470 are provided, one for each of the NAND gates 469.The four inputs of each of the NAND gates 469 are each connected eitherto one of the input lines 461-464 or to the input of the inverterconnected with such input line. The four inputs of all of the NAND gates469 are connected in unique combinations of the input lines and inverteroutputs, so that only one of the NAND gates 469 is operative to producea low level output signal at its output 470 in response to anyparticular combination of signals applied to the input lines 461-464.

Each of the NAND gates 469 may be constructed in the manner illustratedin FIG. 5, which is a schematic circuit diagram of the functionalcontent of the NAND gates 469. Each gate is similar to a commerciallyavailable unit such as is included within a Texas Instruments SN7420. Asshown in FIG. 5, four input lines 471-474 are applied to individualemitters of the multiple emitter transistor 475. The base of thetransistor 475 is connected to a source of positive potential at aterminal 476, through a resistor 477, and its collector is connected tothe base of the transistor 478, the collector of which is connected tothe terminal 476 through a resistor 479, and the emitter of which isconnected to ground through a resistor 480. The collector of thetransistor 478 is connected to the base of the transistor 48], and theemitter of the transistor 478 is connected to the base of the transistor482. The collector of the transistor 481 is connected to the terminal476 through a resistor 483, and its emitter is connected through a diode484 to an output terminal 485. The output terminal is also connectedwith the collector of the transistor 482, the emitter of which isgrounded.

When all four of the input lines 471-474 have relatively positivepotentials applied thereto, the transistor 475 is cut off, therebysaturating the transistor 478, and allowing the transistor 482 to becomesaturated, thereby clamping the output terminal 485 to ground. When anyone of the input lines is low, the transistor 475 is saturated, therebycutting off the transistor 478, resulting in saturating the transistor481 and cutting off the transistor 482, which applies a positivepotential to the output terminal 485.

Although the NAND gate of FIG. 5 has been described in terms of discretecomponents, it is understood that such components are merely thefunctional equivalents of an integrated circuit, and do not necessarilyexist in the form illustrated in FIG. 5, even within the integratedcircuit.

FIG. 6 illustrates a functional block diagram of a .l-K flip-flop suchas one-half of a unit such as the Texas Instruments SN7473. Theflip-flop illustrated in FIG. 6 may be employed for the J-K flip-flopsemployed in the counter 76, and comprises a combination of two R-Sflip-flops one of which serves as a master flip-flop, with the otherserving as a slave flip-flop. The master flipflop incorporates a pair ofNOR gates 487 and 488, the outputs of which are cross-coupled to theirinputs via a NAND gate 489 and an inverter 490. The master flipflop isset by means of an input applied to a J terminal 491, which is connectedto one input of a NAND gate 492 having its output connected to a secondinput of the NOR gate 487. The K input terminal 493 of the flipflop isconnected to an input of a NAND gate 494, the output of which isconnected to a second input of the NOR gate 488.

The slave flip-flop comprises cross-coupled NAND gates 495 and 496, theoutputs of which are respeg tively connected to the output terminal 497and Q output terminal 498. A switching circuit for causing the slaveflip-flop to assume the condition of the master flip-flop, incorporatesa pair of NAND gates 499 and 500, and a pair of pnp transistors 501 and502. The emitters of the two transistors 501 and 502 are connected tothe clock terminal 503. Although the master and slave flip-flops arenormally isolated from each other, when the clock pulse terminal 503 ispresented with a high potential, the master flip-flop is set inaccordance with the input data present at the J-K input terminals 491and 493. if both terminals are high, the state of the flip-flop istoggled. Meanwhile, the condition of the slave flip-flop remains thesame until the potential on the clock terminal 503 goes low, and at thatinstant the slave flip-flop is caused to assume the same condition asthe master flip-flop. A clear input terminal 504 is connected with aninput of each of the NAND gates 489, 492, 499 and 496, to reset thecondition of the master and slave flip-flops irrespective of thecondition of the terminals 491, 493 and 503.

Although the preferred embodiment of the present invention has beendescribed in terms of an instrument such an electronic organ having twokeyboards, referred to as the upper and lower manuals, it is apparentthat the present invention is not so restricted and is equally welladapted for use with other instruments such as a piano, an accordian, orthe like. The switches described above as being operated by the keys ofthe lower manual may instead be operated by chord selecting pushbuttons, or by the left hand portion ofa single keyboard. The tones ofthe arpeggio have been described above as being the same ones which areselectable by the switches operated by the keys of the upper manual, butinstead may be derived from a signal generator other than the oneconventionally employed for use with the switches operated by the keysof the upper manual.

The arpeggio system of the present invention is well adapted for use asan add-on feature to an otherwise complete instrument.

The timer multivibrator 54 may, if desired, be replaced by other meansfor generating a periodic signal. For example. if the musical instrumentis provided with a rhythm section for generating a periodic signal inresponse to a predetermined rhythm, which is a common adjunct ofelectronic organs, that signal may be employed by connecting such signalto the base of the transistor 144, in which case the multivibrator 54 isnot needed. Alternatively, means may be provided for causing themultivibrator 54 to operate in synchronism with the signal from therhythm section.

Although the preferred embodiment of the present invention has beendescribed above, it will be apparent to those skilled in the art thatvarious modifications and changes may be made without departing from theessential features of novelty thereof, which are intended to be definedby the appended claims.

What is claimed is:

1. A musical instrument comprising:

a. generator means for producing a series of signals corresponding to aplurality of musical tones;

b. a keyboard;

c. a set of key-operable switches operable by the keys of said keyboard;

(1. a series of control gates for selectively interconnecting thekey-operable switches in circuit with said generator means for producingtones in response to operation of said gates;

e. scanning means for sequentially scanning said keyoperable switchesand for operating said control gates in response to operated ones ofsaid keyoperable switches; and

f. control means connected with said scanning means for successivelyhalting the operatingof said scanning means at operated ones of said keyoperated switches.

2. Apparatus according to claim 1, wherein said scanning means include arelatively high frequency scanning oscillator, and means connected tosaid oscillator and responsive thereto for scanning said key-operableswitches at a rate corresponding to the frequency of said scanningoscillator, and including a relatively low frequency timing oscillatorconnected with said control means, said control means being operative tohalt said scanning means for an interval corresponding to approximatelythe period of one cycle of operation of said timing oscillator.

3. Apparatus according to claim 1, including means connected with saidcontrol means for operating successive ones of said control gates withsubstantially no delay between the period during which one such gate isoperated and the period in which the next successive gate is operated,relative to the duration of operation of each gate, whereby an arpeggiois produced with substantially no delay between successive tones of saidarpeggio.

4. Apparatus according to claim 1, including mode selector meansconnected with said scanning means for causing said scanning means toscan in one direction during a first period and to scan in the oppositedirection during a second period, and disable means connected with saidscanning means for inhibiting said scanning means from halting at thefirst of said operated switches which is scanned during said secondperiod.

5. Apparatus according to claim 4 wherein said disable means isinterconnected between said scanning means and said control means and isoperative to transfer a strobe signal to said control means each timeone of said operated switches is scanned, and means interconnecting saiddisable means when said mode selector means and responsive to a signalfurnished by said mode selector means in connection with a change inscanning direction thereby, for inhibiting transfer of one of saidstrobe signals.

6. A musical instrument comprising:

a. generator means for producing a series of signals corresponding to aplurality of musical tones;

b. a keyboard;

c. a set of key-operable switches operable by the keys of said keyboard;

d. a series of control gates connected with said switches and with saidgenerator means for selectively interconnecting the key-operableswitches in circuit with said generator means for producing tones inresponse to operation of said gates;

. scanning means for sequentially scanning said keyoperable switches andfor sequentially selecting and operating said control gates in responseto operated ones of said key-operable switches; and

f. control means connected with said scanning means for temporarilypreventing said scanning means from selecting another control gate for apredetermined interval each time an operated one of said key-operableswitches is scanned.

7. Apparatus according to claim 6 wherein said scanning means comprisesmeans for sequentially energizing a plurality of scanning lines, andcircuit means interconnecting said scanning lines with said keyoperableswitches.

8. Apparatus according to claim 6 wherein said scanning means comprisesa counter operative to manifest output signal corresponding to thenumber of pulses applied to an input terminal thereof and a decoderconnected to receive said output signals from said counter andresponsive thereto for successively energizing one of a plurality ofscanning lines, and circuit means for connecting said scanning lineswith said key-operable switches.

9. Apparatus according to claim 8 including means for connecting saidkey-operable switches with said gates, and means for connecting saidscanning lines with said gates, whereby said gates are actuated inresponse to operation of said switches when their respective scanninglines are energized.

10. Apparatus according to claim 6, including an output system forproducing musical tones in response to signals applied thereto, and aplurality of keyers connected with said output system and with saidgenerator means for selectively connecting the signals from saidgenerator to said output system, and means connecting said keyersindividually with said control gates, said keyers being responsive tothe operation of corre-' sponding ones of said gates.

11. Apparatus according to claim 10 including means for connecting oneof said key-operable switches directly to the control input of saidkeyer, whereby said keyer is directly operated by said one switch, andsaid keyer is operated by a control gate when a different one of thekey-operable switches is closed.

12. Apparatus according to claim 10 including means for connecting eachscanning line with a plurality of keyers connected with octavely relatedones of said signals, and octave control means connected individuallywith corresponding keyers within each plurality for individuallyenabling said keyers for operation.

13. Apparatus according to claim 6 including a manually operable modeselector switch for selecting one of a plurality of operating modes ofoperation said scanning means being connected with said mode selectorswitch and operable to scan said key-operable switches in one directionor the other in response to the condition of said switch.

14. Apparatus according to claim 6 wherein said scanning means comprisesan oscillator, a counter having an input connected with said oscillatorfor counting the cycles thereof, and decoder means connected with saidcounter for producing an output signal on one of a plurality of outputlines in response to the state of said counter.

15. Apparatus according to claim 14 including a flipflop, means forconnecting said oscillator with said flipflop for disabling saidoscillator when said flip-flop is in one of its two stable states, andmeans responsive to the operation of one of said key-operable switchesfor producing a pulse for setting said flip-flop to its said one state.

16. Apparatus according to claim 15, including a second oscillator,means for inter-connecting said second oscillator and the firstoscillator for disabling said first oscillator when said secondoscillator is in a predetermined state, means for connecting said secondoscillator when said flip-flop for resetting said flip-flop once duringeach cycle of said second oscillator, and means for operating said firstoscillator for a plurality of cycles during an interval beginning withthe resetting of said flip-flop in response to the end of a half cycleof operation of said second oscillator, and ending with a pulse producedby operation of one of said key-operable switches, whereby the state ofsaid counter is advanced by a number of units corresponding to thenumber of cycles of operation of said first oscillator during saidinterval.

17. Apparatus according to claim 6, including an octave counteroperative to count the number of cycles of operation of said scanningmeans, a decoding matrix connected with said counter for producingoutput signals sequentially on individual ones of a plurality of controllines, and a plurality of mode selector switches connected with saidcontrol lines and adapted to control the direction of scanning of saidscanning means.

18. Apparatus according to claim 6, wherein said instrument includesmeans for generating periodic timing signals for controlling the timingof certain ones of said gates, including timing means connected toreceive said timing signals and for controlling the length of saidpredetermined interval in response thereto.

19. Apparatus according to claim 18, wherein said timing signals arederived from rhythm section of said instrument, and said timing meansincludes means for establishing the length of each of said predeterminedintervals equal to the period of said periodic timing signals.

1. A musical instrument comprising: a. generator means for producing aseries of signals corresponding to a plurality of musical tones; b. akeyboard; c. a set of key-operable switches operable by the keys of saidkeyboard; d. a series of control gates for selectively interconnectingthe key-operable switches in circuit with said generator means forproducing tones in response to operation of said gates; e. scanningmeans for sequentially scanning said key-operable switches and foroperating said control gates in response to operated ones of saidkey-operable switches; and f. control means connected with said scanningmeans for successively halting the operating of said scanning means atoperated ones of said key operated switches.
 2. Apparatus according toclaim 1, wherein said scanning means include a relatively high frequencyscanning oscillator, and means connected to said oscillator andresponsive thereto for scanning said key-operable switches at a ratecorresponding to the frequency of said scanning oscillator, andincluding a relatively low frequency timing oscillator connected withsaid control means, said control means being operative to halt saidscanning means for an interval corresponding to approximately the periodof one cycle of operation of said timing oscillator.
 3. Apparatusaccording to claim 1, including means connected with said control meansfor operating successive ones of said control gates with substantiallyno delay between thE period during which one such gate is operated andthe period in which the next successive gate is operated, relative tothe duration of operation of each gate, whereby an arpeggio is producedwith substantially no delay between successive tones of said arpeggio.4. Apparatus according to claim 1, including mode selector meansconnected with said scanning means for causing said scanning means toscan in one direction during a first period and to scan in the oppositedirection during a second period, and disable means connected with saidscanning means for inhibiting said scanning means from halting at thefirst of said operated switches which is scanned during said secondperiod.
 5. Apparatus according to claim 4 wherein said disable means isinterconnected between said scanning means and said control means and isoperative to transfer a strobe signal to said control means each timeone of said operated switches is scanned, and means interconnecting saiddisable means when said mode selector means and responsive to a signalfurnished by said mode selector means in connection with a change inscanning direction thereby, for inhibiting transfer of one of saidstrobe signals.
 6. A musical instrument comprising: a. generator meansfor producing a series of signals corresponding to a plurality ofmusical tones; b. a keyboard; c. a set of key-operable switches operableby the keys of said keyboard; d. a series of control gates connectedwith said switches and with said generator means for selectivelyinterconnecting the key-operable switches in circuit with said generatormeans for producing tones in response to operation of said gates; e.scanning means for sequentially scanning said key-operable switches andfor sequentially selecting and operating said control gates in responseto operated ones of said key-operable switches; and f. control meansconnected with said scanning means for temporarily preventing saidscanning means from selecting another control gate for a predeterminedinterval each time an operated one of said key-operable switches isscanned.
 7. Apparatus according to claim 6 wherein said scanning meanscomprises means for sequentially energizing a plurality of scanninglines, and circuit means interconnecting said scanning lines with saidkey-operable switches.
 8. Apparatus according to claim 6 wherein saidscanning means comprises a counter operative to manifest output signalcorresponding to the number of pulses applied to an input terminalthereof and a decoder connected to receive said output signals from saidcounter and responsive thereto for successively energizing one of aplurality of scanning lines, and circuit means for connecting saidscanning lines with said key-operable switches.
 9. Apparatus accordingto claim 8 including means for connecting said key-operable switcheswith said gates, and means for connecting said scanning lines with saidgates, whereby said gates are actuated in response to operation of saidswitches when their respective scanning lines are energized. 10.Apparatus according to claim 6, including an output system for producingmusical tones in response to signals applied thereto, and a plurality ofkeyers connected with said output system and with said generator meansfor selectively connecting the signals from said generator to saidoutput system, and means connecting said keyers individually with saidcontrol gates, said keyers being responsive to the operation ofcorresponding ones of said gates.
 11. Apparatus according to claim 10including means for connecting one of said key-operable switchesdirectly to the control input of said keyer, whereby said keyer isdirectly operated by said one switch, and said keyer is operated by acontrol gate when a different one of the key-operable switches isclosed.
 12. Apparatus according to claim 10 including means forconnecting each scanning line with a plurality of keyers connected withoctavely related ones of said signals, and octave control meansconnected individually with corresponding keyers within each pluralityfor individually enabling said keyers for operation.
 13. Apparatusaccording to claim 6 including a manually operable mode selector switchfor selecting one of a plurality of operating modes of operation saidscanning means being connected with said mode selector switch andoperable to scan said key-operable switches in one direction or theother in response to the condition of said switch.
 14. Apparatusaccording to claim 6 wherein said scanning means comprises anoscillator, a counter having an input connected with said oscillator forcounting the cycles thereof, and decoder means connected with saidcounter for producing an output signal on one of a plurality of outputlines in response to the state of said counter.
 15. Apparatus accordingto claim 14 including a flip-flop, means for connecting said oscillatorwith said flip-flop for disabling said oscillator when said flip-flop isin one of its two stable states, and means responsive to the operationof one of said key-operable switches for producing a pulse for settingsaid flip-flop to its said one state.
 16. Apparatus according to claim15, including a second oscillator, means for inter-connecting saidsecond oscillator and the first oscillator for disabling said firstoscillator when said second oscillator is in a predetermined state,means for connecting said second oscillator when said flip-flop forresetting said flip-flop once during each cycle of said secondoscillator, and means for operating said first oscillator for aplurality of cycles during an interval beginning with the resetting ofsaid flip-flop in response to the end of a half cycle of operation ofsaid second oscillator, and ending with a pulse produced by operation ofone of said key-operable switches, whereby the state of said counter isadvanced by a number of units corresponding to the number of cycles ofoperation of said first oscillator during said interval.
 17. Apparatusaccording to claim 6, including an octave counter operative to count thenumber of cycles of operation of said scanning means, a decoding matrixconnected with said counter for producing output signals sequentially onindividual ones of a plurality of control lines, and a plurality of modeselector switches connected with said control lines and adapted tocontrol the direction of scanning of said scanning means.
 18. Apparatusaccording to claim 6, wherein said instrument includes means forgenerating periodic timing signals for controlling the timing of certainones of said gates, including timing means connected to receive saidtiming signals and for controlling the length of said predeterminedinterval in response thereto.
 19. Apparatus according to claim 18,wherein said timing signals are derived from rhythm section of saidinstrument, and said timing means includes means for establishing thelength of each of said predetermined intervals equal to the period ofsaid periodic timing signals.